Silencer



Dec. 21,1926. 1, 11,475

H. P. MAXIM S ILENCER Filed March 26, 1922 BY "W ATTORNEYS PatentedDec.. 21, 1926.

UNITED STATES mama run SILENCER nnorrour.

OMPANY, OF HARTFORD,

PATENT OFFICE.

CONNECTICUT, A CORPORATION OF CON- SILENCER.

Application filed. March 23, 1922. Serial No. 546,126.

The present invention relates to silencers or mutflers such as are usedin connection with gas or oilenginesto reduce the noise of the exhaustor in connection with various kinds of steam and pneumatic machinery fordeadening the discharge or intake noises thereof.

One object of the invention is to provide a mufller or silencer of theeneral character above mentioned which wil effectively performitsfunction without creating back pressure.

To this end, the invention contemplates broadly the provision, in anexhaust or intake muflier, of asilencing conduit constructed andarranged to obstruct the escape of the sound waves without throttlingthe flow of the sound propagating medium.

' In carrying out this feature of the invention the silencing conduit ismade to comprise at least one section, the walls of which are shaped inaccordance with the principles of Venturi tube construction to provide agradually contracting portion and 85 a gradually expanding portion, theformer beingv arranged to discharge into the latter. As the exhaustgases pass through a conduit constructed in this manner the sound waveswhich strike the tapering walls of the con tracting portions arereflected backwardly and are trapped and as a result only such soundwaves escape as pass directly through the small end of the contractedportion with-' out striking against the converging walls thereof. Byreason of the Ventnri action of the expanding or diverging portion ofthe conduit, the velocity of the gases is increased in the restrictedportion to such an extent that the volume of flow per unit of time ofsaid gases or propagating medium is not materially reduced andconsequently the discharge capacity of the conduit is not-reduced and noundesirable back pressure is created.

Another object (if the invention is to pro ide, in an exhaust mufflerfor internal combustion engines, 'lneansxwhereby the head or advanceportion of the intermittent "or pulsating stream ofexhaust gases willserve to draw out the tail or rear portion. of the latter, and thus toassist in scavenging the engine cylinders.

Another object of the invention is to provide certain new and usefulimprovements in.

and claimed, the advantages of which will,

be apparent to those skilled in the art.

In the accompanying drawings,

Fig. 1 is a longitudinal sectional view of a silencer embodying onefeature ofthe present invention Fig. 2 is a section on the line 2-2 ofFig. 1; I

Fig. 3 is a view similar to Fig. 1 showing a modification of theconstruction illustrated therein; I

Figs. 4, 5, and 6 are longitudinal sectional views of silencersembodying in alternative forms certain additional features of thepresent'invcntion.

Referring first to Figs. 1 and 2 of the drawings, the silencer ormuflier therein illustrated consists of a conduit comprising a pluralityof sections 2, each having gradually.

contracting portions 3 and. gradually expanding portions 4 relativelyarranged to producethe effect of the well-known Venturi tube upon afluid or gas flowing therethrough. The inventor" has discovered that byproviding, in a silencing conduit, one or more tubular sections havingconverging walls as in the case of the illustrated sections 3, most ofthe sound waves will strike the converging walls and be reflectedbackwardly so that they will be effectively trapped, the only soundwaves finallyiescaping beingthose which pass directly through theseveral re stricted portionspf the conduit without first engaging anyportions of the walls thereof.

It is very important in most engines'and in many forms of machinery inconnection with which mufliers are ei'nployed that the exhaust ordischarge shall not be obstructed so as to produce back pressure in theengine cylinders or pressure chambers of the machinery.

,To prevent the creation of back pressure the present inventioncontemplates the employment, in conjunction with the contracted sections3, of the tabular sections 4 having graduall diverging side walls,thelatter regularly recurring contractions and exsections eing arrangedto receive the sound propagating medium directly from the small agatinggases. 7 1

ends of the converging sections 3 and to Fig. 4 is illustrative ofa'silencer which draw said medium through said converging embodiesanother feature of the present insections so that its flow will not besubstanvcntion. As shown, a continuous tube 6 is tlally retardedtherein. provided with a series of Venturi sections 7 pansions in thestream of thesound prop-,

As the gases which carry the sound waves which may be similar to thosealready de- 1 flow through the expanding sections 4 of the scribed inconnection with the Figs. 1 and 2.

conduit these sections act in substantially the The tube 6, which servesas a conductor for same manner as a Venturi tube to expand the exhaustgases or other sound propagatthe'stream of gas and to lower its pressureing medium, fits tightly within a cylindrical and thereby to assist inincreasing the distube '8 to form annular compartments oi chargecapacityof the conduit. Furtherchambers 9 between the enlarged portionsmore, the noise values are spread over a of the tube 6, each chamber 9being sub-' much greater area and consequently their stantially gastight except for connections value per square inch becomes much reduced.through a plurality of ports 10 to the inner As the gases pass throughthe contractin sections 3, the sound waves are reflected an the noisevalue of those waves which escape tube 6 at the region of lowestpressure in the respective Venturi section of said tube. \Vith thisconstruction the sound waves through the small ends of these sectionsbear are reflected backwardly by each converging the same relation tothe noise value of the wall portion of the tube and by reason of wavesentering said sections .as the minimum the shape of the succeedingdiverging wall cross-sectional areas of these sections bear to portionsthe flow of the gases is not matethe maximum cross-sectional areasthereof. rially impeded. Furthermore by reason of Thus, each time thegases enter a new conthe low pressure which exists in the retractingsection, a relatively large quantity stricted portions of the Venturisections 7 of the remaining sound waves are reflected the gases in thechambers 9 are partially exbackwardly and trapped and only a.relahausted through the ports 10 at each pulsatively small quantity arepermitted to escape. tion of the exhaust, leaving a partia vacuumConsequently by -employing a sufficient numwithin each of said chambers.This partial ber of contracting sections in the silencing vacuum in thechambers 9 satisfies itself conduit nearly all of the sound waves willfrom or, in other words, is relieved by the ultimately be trapped sothat the noise will following gases. Thus the head of each be practicallsilenced by the time the exexhaust pulsation becomes effective to pullhaust gases all emerge fromthe silencer. out the tail thereof and thusto secure I It will be un erstood that by reason of complete scavengingof the engine cylinders the Venturi action of the diverging sections orother pressure chambers- The inner tube 4, the velocity of the flowthrough the re- 6 may be rigidly secured in any suitable strictedportions of the conduit will be inmanner to the outer tube 8 or thetubes 6 creased in proportion to the amount of reand 8 may bedetachably'held in assembled duction in cross-sectional area of theconrelation by means such as a spring latch 12' duit at these points.Thus substantially the which may be released to permit convenient samevolume. per unit of time will pass removal of the inner tube forcleaning purthrough said restricted portions as passes. inl poses.

' the same time through'theunrestricted por- .A modification of theconstruction just dctions of the conduit. Accordingly, the least scribedis shown in Fig. 5. In this figure possible resistance is offered to theflow of the silencing conduit comprises a seriesol' the gases, thedischarge thereof is practiseparate sections 14 each having a contractedcally unretarded and no back pressure is inlet 15', an enlargedintermediate portion created. 16 and a contracted outlet 17. The inlet15 It is of course, hf importance that the of each section 14 is ofsomewhat largerdiwalls of the converging portions of the Venameter thanthe outlet 17 thereof and the turi sections shall be so shaped andpitched several sections are arranged in axial alineas to reflect theSound waves to best advanment. The outlet of each preceding section tageWithout creating 00 mll h fr c ional reis arranged totelescope withinthe inlet of sistance to the flow of the gases in which the eachsucceeding section. Thus the forward sound waves travel and also thatthe dihalf of each section 14 and the rear half verging portions of theVenturi sections shall of the section 14 next in advance thereof in beproperly proportioned to produce the decombination constitute a Venturisection sired effect .upon the flow of the gases. such, in eflfechas theVenturi sections in the In the modified construction shown in Fig. formsof silencers heretofore described. 3, fhe several Venturi sections 5have been The separately constructed sections 14 may non-uniformlyspaced in the conduit to break be independently secured wlthin an outerI up the resonance resulting from a series of cylindrical tube 18 bymeans of screws or sections or units 23 which correspond to the conduitsections 14 of the construction shown in Fig. 5. Each unit 23 includes,in

I addition to the expanding and contracting ortions 24 and 25 throughwhich the exaust gases flow, a tube 26 which cooperates with similartubes on other units 23 toconstitute an outercylindrical shell in whichlow pressure chambers 32 are formed. As shown, the outer tube 26 of eachunit 23 is made integral with the contracting portion 25 While theexpandin portion 24 is riveted at 27 to large end of the contractingportion 25. The tubes 26 of the several units 23 have universal jointconnections with each other thus providing mmufller'conduit which isflexible and may be bent to avoid obstructions or otherwise adapt itselffor convenient vinstallation. To this end each tube 26 is formed withspherically curved end portions 28 and 29, the portions 29 of each tube-26 constituting a socket for receiving the portion 28 of the adjacenttube 26 thereby orming a ball and socket joint connection between. saidtubes 26. The tubes 26 are made of such length as to insure that theunits 23 will be arranged with their outlet and inlet'ends telescopingbut separated by 'the details of construction and arran ement' of partsmay be resorted to without eparting from the spirit and scope of theinvention as hereinafter claimed.

Claims:

1. A muflier forsilencingtheexhaust of an internal combustion'engmecomprislp' g a conduit for thefe'xhaust gases having a nturi-likepassageway ther'ein'and a clia ber l closed on all sides except. for an-openin therefrom into the restricted portion of sai A passageway. v

2. In a muflier for silencing the exhaust of an internal. combustionengine, a conduit comprising ayconverging section and B/dif .vergingsection, said converging section opening into said diverging section toprovide a Venturi-like passageway therebetween and a chamber closed onall sides except for an opening therefrom into the re stricted portionof said passageway.

3. In a mufiler for silencing the exhaust .of an'in'ternal combustionengine, a conduit comprising a series of alternate converging anddiverging sections, each converging section opening into the nextsucceeding diverging section to form. a series of Venturi-like passaeways in said conduit, and a separate cham r surroundin each passageway,each being closed at all sides except for an opening therefrom into therestricted portion of its respective passageway.

4. A mufiier for silencingthe exhaust of an internal combustion enginehaving, in combination, a conduit for the exhaust gases comprising aconverging section and a di-' verging section, the converging sectionhaving its contracted end telescoping within the contracted end of thediverging section and separated therefrom by an annular space, and agastight chamber surrounding said contracted ends and communicating withthe interior of said diverging section through said annular space.

5. A mufiler comprising a flexible conduit for a sound propagatingmedium comprising a plurality of. separate longitudinal sectionsdirectly joined together by flexible joints to permit a limited amountof uni-. versal movement between adjacent sections,

and saidsections having passagewa s con structed and arranged toobstruct t e pas sage of the sound waves. v

6. A muflier comprising a flexible conduit for the sound propagatingmedium comprising a pluralit of se arate lon itudinal sections direct yjoine together by a flexible. jointto permit a limited amount ofuniversal movement between adjacent sections, said sections combining.to afford a succession of Venturi-like passages for obstructing thesound. waves without throttling the flow of the sound propagatingmedium. p I

'7. A mufiier comprising a flexible conduit for the sound propagatingmedium consisting of a. plurality of longitudinal sections joinedtogether to permit. a limited amount of universal movement betweenadjacent sections, said sections combining to afford a successionofVenturi-like passages for obstructin .the' sound waves withoutthrottling the ow of the sound propagating medium, anda series of lowpressure chambers communicating with the'restricted portions of said.passages.

8. An exhaust mufiler having, in combiv nation, a series of units eachcomprising di-. verging and converging inner conduit sections and anouter tubular section having two spherically curved portions spacedlongitudinally thereon, one of said curved portionsoneach tubularsection being adapted and arranged to provide when assembled a mufiierconduit having a succession of Venturi-like silencing passages. y

In testimony whereof I have affixed my signature.

HIRAM PERCY MAXIM

